Our previous research on the Wechsler Adult Intelligence Scale has produced: (1) a large-scale data base of WAIS information useful for aging research, (2) some novel structural equation models appropriate for aging research, (3) some results about the complex measurement functions of the WAIS, and (4) some results about the complexity of growth curve functions of intellectual ability. During the past four years of this project we have measured a strategically selected set of adults who had been tested before on a wider battery of ability measures, including (5) three-wave longitudinal retest data on the National Growth and Change Study (NGCS) sample, (6) a seventh-wave of longitudinal data on the smaller Bradway sample, and (7) current measurements of the Berkeley Growth Study participants. We have also (8) developed dynamic models for unraveling patterns of leading and lagging indicators of aging processes. In this competing continuation proposal we will continue to use and develop new statistical methods for the synthesis of research on the measurement of dynamic changes in the growth curves of intellectual abilities. We will concentrate on the use of the existing databanks to provide an evaluation of the structural, kinematic, and dynamic hypotheses of the "theory of fluid and crystallized intelligence", and we collect new data from newly completed neurological and experimental studies. The analyses planned include (1) improved ability measurements based on item response theory and improved factorial structure through convergent operations, (2) a formal evaluation of the growth and declines of abilities through latent growth and bear dynamic models, (3) a formal evaluation of the age-based leading and lagging indicators of multivariate developmental sequences through some new multivariate dynamic structural equation models, (4) the creation of a new archive of experimental and neurological measures to evaluate convergent measurement relationships using confirmatory modeling techniques, and (5) provide new methods for further research on aging. These new results will help synthesize all past research on the WAIS, explicitly define the relationships of the WAIS with currently collected measures, and clarify the growth and decline of intellectual abilities across the adult life-span.